Butterfly valves may be used in valve systems in which high flow with minimal pressure drop across the valve is desired. Butterfly valves generally include a round valve disk positioned in the center of a bore in which flow is to be controlled. The disk is affixed to a shaft such that rotation of the shaft causes rotation of the disk between at least a first position in which flow in the bore is blocked and a second position in which the bore is open to flow. The disk typically rotates about one quarter turn (90°) between the first and second positions and is often rotated incrementally between the two positions to throttle flow. An actuator outside the bore is couple to the shaft, often via a linkage or gearing, to rotate the shaft and the valve disk.
The actuator for typical automatically operated butterfly valves includes a motor coupled to the shaft directly or via gearing to impart rotation to the shaft. The actuator is sized to impart a full quarter turn to the valve disk, making the overall size of the valve and actuator larger than necessary when less than a quarter turn is desired. Therefore, a need exists for a compact, solenoid operated butterfly valve having a valve disk operative over less than one quarter turn.